Well I was thinking how Nekocon is right after Halloween so it is common to see non traditional costumes. How does everyone feel about Halloween costumes being displayed? The things that come to mind are Freddy Kruger, Jason, and Star Wars. That brings me to my next point. Is wearing a star wars costume taboo at an anime convention? It seems like it would be awkward but I've seen so many storm troopers!

I personally see nothing wrong with it. Especially with scifi series- you see at least one Stormtrooper or Vader a year. Heck, one year there was a Ghostbuster! :3 We're all nerds, why not be nerds together!
In fact- I'm planning on being Fem!10th Doctor for Halloween as was considering wearing it to Nekocon.

I am highly considering slave leia because I wouldn't be able to get a new costume in short notice except from halloween stores. It seems acceptable. Except it is very little clothing and Nekocon is always FREEZING!

One of the most basic rules for survival on any planet is never to upset someone wearing black leather. (This is why protesters against the wearing of animal skins by humans unaccountably fail to throw their paint over Hell's Angels.) -- Terry Pratchett